The invention relates generally to medical devices and more particularly to expandable medical devices and methods for increasing blood flow through an obstructed blood vessel.
Some known medical devices used for increasing blood flow through an obstructed blood vessel include a filter trap designed and built to trap emboli. Such filters tend to be cumbersome and difficult to deploy. In addition, in some such devices, if the device is not properly seated in the vessel, the device can drift within the vessel. Some such devices are generally designed to catch emboli greater than a particular size (limited by the aperture size of the device walls), and are therefore not effective for removing smaller embolic particles.
In one known filter device, a basket is carried on a mandrel, which can be deployed and retracted through a catheter. In another known device, a vascular filter is collapsible, and includes a radially expandable body and proximal and distal sliders on a mandrel. The medical device can be used to filter fluid, but has the disadvantage of independent proximal and distal motion control, making it difficult to coordinate precisely and predictably a desired movement. Even if the filter trap effectively captures dislodged material within a vessel, retracting the filter trap into the catheter through which it was delivered can be difficult. Some known devices use vascular suction to suction or pull blood and clots out of the vessel.
Currently, few FDA-approved treatment options exist for an acute ischemic stroke. One option is an intravenous (IV) delivery of Tissue Plasminogen Activator (t-PA) (Activase), which is a thrombolytic agent. The agent is designed to dissolve the blood clot that is blocking blood flow to the brain. IV t-PA is currently limited in use because it must be used within a three hour window from the onset of a stroke and can result in an increased risk of bleeding. The second option is a thromboembolectomy device. The device is designed to capture an embolus or clot and remove it from the blocked vessel, thereby restoring blood flow. The device includes a cork-screwed guidewire, but is only able to capture and remove matter that is firm or held together by itself. In most cases, the device is used in combination with drug therapy to restore blood flow. A typical procedure using the device can take 2-3 hours to restore blood flow, if at all, and may take multiple passes through the vessel to either capture, macerate or open the vessel. In some cases, the device may capture an embolus, but then lose grasp of it and deposit it incidentally in another area of the neurovasculature, creating the potential for a new stroke in a new territory. In some cases, complications such as vessel dissection, perforation and hemorrhage arise as a result of over-manipulation in the vessel.
Thus, there is a need for improved systems, devices and methods for increasing blood flow through a blood vessel as described herein.